Systems, devices, and methods for energy efficient electrical device activation

ABSTRACT

Systems, devices, and methods are provided for changing the power state of a sensor control device in an in vivo analyte monitoring system in various manners, such as through the use of external stimuli (light, magnetics) and RF transmissions.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 17/532,427, filed Nov. 22, 2021, which is a continuation ofU.S. patent application Ser. No. 16/201,688, filed Nov. 27, 2018, nowU.S. Pat. No. 11,207,006, which is a continuation of U.S. patentapplication Ser. No. 14/265,026, filed Apr. 29, 2014, now U.S. Pat. No.10,213,141, which claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/973,775, filed Apr. 1, 2014, U.S. ProvisionalPatent Application No. 61/896,578, filed Oct. 28, 2013, and U.S.Provisional Patent Application No. 61/817,839, filed Apr. 30, 2013, allof which are incorporated by reference herein in their entireties forall purposes.

FIELD

The subject matter described herein relates generally to changing thestate of power consumption of an electrical device in an efficientmanner, for example, within an analyte monitoring environment.

BACKGROUND

The detection and/or monitoring of analyte levels, such as glucose,ketones, lactate, oxygen, hemoglobin A1C, or the like, can be vitallyimportant to the health of an individual having diabetes. Diabeticsgenerally monitor their glucose levels to ensure that they are beingmaintained within a clinically safe range, and may also use thisinformation to determine if and/or when insulin is needed to reduceglucose levels in their bodies or when additional glucose is needed toraise the level of glucose in their bodies.

Growing clinical data demonstrates a strong correlation between thefrequency of glucose monitoring and glycemic control. Despite suchcorrelation, many individuals diagnosed with a diabetic condition do notmonitor their glucose levels as frequently as they should due to acombination of factors including convenience, testing discretion, painassociated with glucose testing, and cost. For these and other reasons,needs exist for improved analyte monitoring systems, devices, andmethods.

SUMMARY

A number of systems have been developed for the automatic monitoring ofthe analyte(s), like glucose, in a bodily fluid of a user, such as inthe blood, interstitial fluid (“ISF”), dermal fluid, or in otherbiological fluid. Some of these systems include a sensor that can be atleast partially positioned “in vivo” within the user, e.g.,transcutaneously, subcutaneously, or dermally, to make contact with theuser's bodily fluid and sense the analyte levels contained therein.These systems are thus referred to as in vivo analyte monitoringsystems.

The sensor is generally part of a sensor control device that resides on(or in) the body of the user and contains the electronics and powersource that enable and control the analyte sensing. The sensor controldevice, and variations thereof, can be referred to as a “sensor controlunit,” an “on-body electronics” device or unit, an “on-body” device orunit, or a “sensor data communication” device or unit, to name a few.

The analyte data sensed with the sensor control device can becommunicated to a separate device that can process and/or display thatsensed analyte data to the user in any number of forms. This device, andvariations thereof, can be referred to as a “reader device” (or simply a“reader”), “handheld electronics” (or a handheld), a “portable dataprocessing” device or unit, a “data receiver,” a “receiver” device orunit (or simply a receiver), or a “remote” device or unit, to name afew. The reader device can be a dedicated use device, a smart phone, atablet, a wearable electronic device such as a smart glass device, orothers.

In vivo analyte monitoring systems can be broadly classified based onthe manner in which data is communicated between the reader device andthe sensor control device. One type of in vivo system is a “ContinuousAnalyte Monitoring” system (or “Continuous Glucose Monitoring” system),where data can be broadcast from the sensor control device to the readerdevice continuously without prompting, e.g., in an automatic fashionaccording to a broadcast schedule. Another type of in vivo system is a“Flash Analyte Monitoring” system (or “Flash Glucose Monitoring” systemor simply “Flash” system), where data can be transferred from the sensorcontrol device in response to a scan or request for data by the readerdevice, such as with a Near Field Communication (NFC) or Radio FrequencyIdentification (RFID) protocol.

Provided herein are a number of example embodiments of systems, devices,and methods that allow the state (or mode) of power consumption for adevice, such as a sensor control device, to be changed in an energyefficient manner. Changing of the state of power consumption caninclude, for example, changing from a low power state (e.g., poweredoff) to a higher power state (e.g., powered on). In some cases, thischange of state is referred to as “activation” and is employed, forexample, when a sensor control device is first put in use by a wearer.For ease of illustration, many of the embodiments described herein willrefer to changing the power state of a sensor control device, althoughthese embodiments are not limited to such.

In certain embodiments an activation sensor is provided with the sensorcontrol device and operation of the activation sensor causes activationof the internal electronics. The activation sensor can be an opticalactivation sensor that produces a response when exposed to ambientoptical light or another light source. The exposure to light (or someother trigger such as a magnetic field) and subsequent activation can beaccomplished before applying the device to the body of a user, forexample, during the unpacking of the applicator assembly. The opticalactivation sensor can be part of an activation circuit for the sensorcontrol device. Upon exposure to light, the optical activation sensor,which may be in the form of an optically activatable switch, can causethe activation circuit to initiate an on-board processor. The processor,in turn, can maintain the internal electronics in the active stateduring the duration of use of the sensor control device, or during thelifetime of the device's power supply. Verification of the initiation ofthe electronics can be performed by the user or automatically by thesystem, such as by generation of a message or other indication to theuser at the reader device. Also provided are methods of manufacturingthe sensor control device with a sensor control activation sensor suchas an optical sensor.

In other embodiments, the sensor control device is capable of utilizingtransmissions over a wireless communication protocol to change a powerstate, or to recognize when such a change should be effected.

For example, the sensor control device can be capable of sending andreceiving communications according to a Bluetooth Low Energy (BTLE)protocol. In certain embodiments, the sensor control device, whileoperating in a first power state (e.g., a low power state such as apowered-off or inactivated state, a storage state, or a sleep state),can receive such a wireless communication from the reader device andrecognize that it is or is part of a BTLE advertising sequence (or is asingle advertising message). The recognition can be made either throughhardware or software. Upon making that recognition, the sensor controldevice can change to a second, higher power state (e.g., a state ofgreater power consumption than the first power state, such as apowered-on or activated state, or an awake state). In certainembodiments, the sensor control device can recognize the advertisingsequence without first demodulating the communication.

In some embodiments the sensor control device receives a second orsubsequent advertising sequence from the reader device when in thesecond power state. The sensor control device can demodulate the secondadvertising sequence and determine if it contains an activation requestmessage and, if so, then transmit a confirmation response to the readerdevice. If the demodulated communication does not contain the activationrequest message, then the state of the sensor control device can bechanged back to the first power state. In some embodiments, the firstpower mode is a sleep (or storage) mode and the second power mode is anormal operation mode.

A number of variations to the aforementioned embodiments are alsoprovided. For example, the advertising sequence can include a series ofadvertising packets transmitted at a predetermined time interval. Theadvertising sequence can include a connectable directed advertisingpacket type, a connectable undirected advertising packet type, anon-connectable undirected advertising packet type, or a scannableundirected advertising packet type, each of which can be the activationrequest message.

In still other embodiments, successive radio frequency (RF)communications can be used to supply power to, for example, the sensorcontrol device. The sensor control device can be in a low-power state(e.g., a power-off or inactivated mode, a storage mode, or a sleep mode)where full operating power is not being supplied. The sensor controldevice can utilize the power of the received wireless communications tocause a local power source to begin supplying the operating power,thereby transitioning the sensor control device to a higher-power state(e.g., a normal, awake, or activated operating state). In many of theseembodiments, the wireless communications are sent and received inaccordance with a Near Field Communication (NFC) protocol, althoughother protocols can be used as well.

Adaptive embodiments are also described where the power mode of thesensor control device is directly or indirectly monitored by the readerdevice and one or more of the number, type, interval, or power of thesuccessive wireless communications is adjusted by the reader deviceuntil sufficient power is supplied to enable the sensor control deviceto transition to a higher-power mode. The embodiments described hereinare particularly suitable when the reader device is in the form of asmartphone.

Other systems, devices, methods, features and advantages of the subjectmatter described herein will be or will become apparent to one withskill in the art upon examination of the following figures and detaileddescription. It is intended that all such additional systems, devices,methods, features and advantages be included within this description, bewithin the scope of the subject matter described herein, and beprotected by the accompanying claims. In no way should the features ofthe example embodiments be construed as limiting the appended claims,absent express recitation of those features in the claims.

BRIEF DESCRIPTION OF THE FIGURES

The details of the subject matter set forth herein, both as to itsstructure and operation, may be apparent by study of the accompanyingfigures, in which like reference numerals refer to like parts. Thecomponents in the figures are not necessarily to scale, emphasis insteadbeing placed upon illustrating the principles of the subject matter.Moreover, all illustrations are intended to convey concepts, whererelative sizes, shapes and other detailed attributes may be illustratedschematically rather than literally or precisely.

FIG. 1 is a high level diagram depicting an example embodiment of ananalyte monitoring system for real time analyte (e.g., glucose)measurement, data acquisition and/or processing.

FIG. 2A is a block diagram depicting an example embodiment of a readerdevice configured as a smartphone.

FIGS. 2B-C are block diagrams depicting example embodiments of a sensorcontrol device.

FIG. 3 is a block schematic view depicting an example embodiment ofsensor electronics having an optically-based activation circuit.

FIG. 4 is a flowchart depicting an example embodiment of a method ofusing the analyte monitoring system with an optical sensor.

FIGS. 5A-I are illustrations of the steps in performing an exampleembodiment of a method of using the analyte monitoring system with anoptical sensor.

FIG. 6A is an exploded view of an example embodiment of an applicator.

FIG. 6B is an exploded view of an example embodiment of a container fora sensor assembly.

FIG. 7 is a block schematic view depicting an example embodiment ofsensor electronics having a magnetically-based activation circuit.

FIG. 8 is a flowchart depicting an example embodiment of a method ofusing the analyte monitoring system with a magnetic sensor.

FIGS. 9A-D are construction views of a sensor control devicesubassembly.

FIG. 9E is a perspective view of a complete sensor electronicssubassembly.

FIGS. 10A-D illustrate the process of co-molding/overmolding theembodiment of FIG. 9E.

FIGS. 11A-C are assembly and sectional views of an alternativesnap-together embodiment for the assembly of FIG. 9E.

FIGS. 12A-C are assembly views illustrating adhesive backing applicationin producing a final sensor control device ready for use.

FIGS. 13-14 are block diagrams depicting example embodiments of methodsfor establishing communication between a sensor control device and areader device.

FIG. 15 is a block diagram depicting another example embodiment of asensor control device.

FIG. 16 is a block diagram depicting an example embodiment of powermanagement circuitry.

FIGS. 17A-B are flow diagrams depicting an example embodiment of amethod of supply power to a sensor control device with successive RFcommunications sent by a reader device.

FIG. 18 is a conceptual timing diagram depicting power levels of areader device and sensor control device, and various communications andcommunication attempts between those devices.

FIG. 19 is a flow diagram depicting an example embodiment of a method ofadaptively supplying power to a sensor control device.

DETAILED DESCRIPTION

The present subject matter is not limited to the particular embodimentsdescribed, as those are only examples and may, of course, vary.Likewise, the terminology used herein is for the purpose of describingparticular embodiments only, and is not intended to be limiting, sincethe scope of the present disclosure will be limited only by the appendedclaims.

In conventional analyte monitoring systems, the sensor control devicehas a small physical form enabling it to be worn inconspicuously by theuser. This constrains the size of the device's internal electronics andpower source. If the sensor control device has a limited lifespandictated by the long-term reliability of the sensor (e.g., fourteendays), then it will be disposable and replaceable with another device.The desirability to minimize the cost of each device adds furtherpressure to minimize the size of the power source and the rate at whichit is used. The power requirements of the sensor control deviceelectronics and the rate at which the software operates thoseelectronics are therefore minimized in the design process.

To this end, the sensor control device is often shipped and stored in alow-power mode where the power source does not supply operating power toall or most of the sensor electronics. In some embodiments, onlywireless communication circuitry is active, operating in a mode thatdraws minimal quiescent current to listen for an activation RF signal.

In this low-power mode the power source can be disconnected mechanicallyfrom the internal electronics (such as by placement of a removableinsulator between the device's contacts and the power source),electronically (such as with a controllable isolation circuit) in amanner that minimizes leakage current from the source, or otherwise. Thepower source can be connected once the wearer is ready to begin use ofthe sensor.

Many of the embodiments described herein provide techniques for changingthe power state of a sensor control device with improved efficiency,cost, and reduced hardware and software (among others) as compared toconventional techniques.

An example embodiment of an in vivo analyte monitoring system 100 withwhich the embodiments described herein can be used is depicted in theillustrative view of FIG. 1 . Here, system 100 includes a sensor controldevice 102 and a reader device 120 that can communicate with each otherover a local wireless communication path (or link) 140, which can beunidirectional or bi-directional. The communications sent across link140 contain digital messages in a frame format (which includes packets)and can be based on a Near Field Communication (NFC) protocol (includingan RFID protocol), Bluetooth or Bluetooth Low Energy (BTLE) protocol,Wi-Fi protocol, proprietary protocol, or others. Reader device 120 isalso capable of wired, wireless, or combined communication overcommunication paths (or links) 141 and 142 with other systems ordevices, such as a computer system 170 (e.g., a server for a website, apersonal computer, a tablet, and the like) or cloud-based storage 190.

Any version of Bluetooth can be used for communication links 140, 141,and 142. One such version is Bluetooth Low Energy (BTLE, BLE), which isalso referred to as Bluetooth SMART or Bluetooth SMART Ready. A versionof BTLE is described in the Bluetooth Specification, version 4.0,published Jun. 30, 2010, which is explicitly incorporated by referenceherein for all purposes. It should be noted that one of ordinary skillin the art will readily recognize that the embodiments described hereincan be used with subsequent iterations of the Bluetooth protocols, orwith new protocols that operate in a similar fashion to the Bluetoothprotocols described herein, regardless of whether those protocols are inexistence as of the time of this filing.

The use of BTLE communication (or other low-energy wireless standards),allows for reduced energy usage, which can be particularly important inperforming data transmissions between sensor control device 102 andreader device 120 over link 140. This, in turn, allows for eitherreduction of the battery size in sensor control device 102 or extensionof the battery life (or combinations thereof).

Use of a low-energy wireless communication protocol can allow therespective communication interfaces to have, for example, a lower dutycycle (i.e., less frequent active operation, which drains less batterypower), shorter periods of usage, or any combination thereof. Inaddition to BTLE, other wireless protocols such as Wi-Fi, cellular,Zigbee, and custom protocols can be used instead of, or in addition to,BTLE for links 140, 141, and 142. These other protocols, however,typically require either more energy than BTLE, are not widelyintegrated into smartphones or tablets, or are not approved forworldwide use. Today and for the foreseeable future, smartphones,tablets, and other portable computing devices will be provided tocustomers with Bluetooth capability, as that family of protocols iswidely regarded as the most convenient to accomplish close proximitycommunication between, e.g., a tablet, and the tablet's peripherals(e.g., wireless headset, mouse, keyboard, etc.).

Other embodiments of sensor control device 102 and reader device 120, aswell as other components of an in vivo-based analyte monitoring systemthat are suitable for use with the system, device, and methodembodiments set forth herein, are described in US Patent ApplicationPubl. No. 2011/0213225 (the '225 Publication), which is incorporated byreference herein in its entirety for all purposes.

Sensor control device 102 can include a housing 103 containing in vivoanalyte monitoring circuitry and a power source (shown in FIGS. 2B-C).The in vivo analyte monitoring circuitry is electrically coupled with ananalyte sensor 104 that extends through a patch 105 and projects awayfrom housing 103. An adhesive layer (not shown) can be positioned at thebase of patch 105 for attachment to a skin surface of the user's body.Other forms of attachment to the body may be used, in addition to orinstead of adhesive. Sensor 104 is adapted to be at least partiallyinserted into the body of the user, where it can make contact with theuser's bodily fluid and, once activated, used with the in vivo analytemonitoring circuitry to measure and collect analyte-related data of theuser. Generally, sensor control device 102 and its components can beapplied to the body with a mechanical applicator 150 in one or moresteps, as described in the incorporated '225 Publication, or in anyother desired manner.

After activation, sensor control device 102 can wirelessly communicatethe collected analyte data (such as, for example, data corresponding tomonitored analyte level and/or monitored temperature data, and/or storedhistorical analyte related data) to reader device 120 where, in certainembodiments, it can be algorithmically processed into datarepresentative of the analyte level of the user and then displayed tothe user and/or otherwise incorporated into a diabetes monitoringregime.

As shown in FIG. 1 , reader device 120 includes a display 122 to outputinformation to the user and/or to accept an input from the user (e.g.,if configured as a touch screen), and one optional user interfacecomponent 121 (or more), such as a button, actuator, touch sensitiveswitch, capacitive switch, pressure sensitive switch, jog wheel or thelike. Reader device 120 can also include one or more data communicationports 123 for wired data communication with external devices such ascomputer system 170 (described below). Reader device 120 may alsoinclude an in vitro analyte meter, including an in vitro test strip port(not shown) to receive an in vitro analyte test strip for performing invitro analyte measurements.

Computer system 170 can be used by the user or a medical professional todisplay and/or analyze the collected analyte data with an informaticssoftware program. Computer system 170 may be a personal computer, aserver terminal, a laptop computer, a tablet, or other suitable dataprocessing device, and can be (or include) software for data managementand analysis and communication with the components in analyte monitoringsystem 100.

The processing of data and the execution of software within system 100can be performed by one or more processors of reader device 120,computer system 170, and/or sensor control device 102. For example, rawdata measured by sensor 104 can be algorithmically processed into avalue that represents the analyte level and that is readily suitable fordisplay to the user, and this can occur in sensor control device 102, orit can occur in reader device 120 or computer system 170 after receiptof the raw data from sensor control device 102. This and any otherinformation derived from the raw data can be displayed in any of themanners described above (with respect to display 122) on any displayresiding on any of sensor control device 102, reader device 120, orcomputer system 170. The information may be utilized by the user todetermine any necessary corrective actions to ensure the analyte levelremains within an acceptable and/or clinically safe range.

As discussed above, reader device 120 can be a mobile communicationdevice such as, for example, a Wi-Fi or internet enabled smartphone,tablet, or personal digital assistant (PDA). Examples of smartphones caninclude, but are not limited to, those phones based on a WINDOWSoperating system, ANDROID operating system, IPHONE operating system,PALM WEBOS, BLACKBERRY operating system, or SYMBIAN operating system,with data network connectivity functionality for data communication overan internet connection and/or a local area network (LAN).

Reader device 120 can also be configured as a mobile smart wearableelectronics assembly, such as an optical assembly that is worn over oradjacent to the user's eye (e.g., a smart glass or smart glasses, suchas GOOGLE GLASSES). This optical assembly can have a transparent displaythat displays information about the user's analyte level (as describedherein) to the user while at the same time allowing the user to seethrough the display such that the user's overall vision is minimallyobstructed. The optical assembly may be capable of wirelesscommunications similar to a smartphone. Other examples of wearableelectronics include devices that are worn around or in the proximity ofthe user's wrist (e.g., a watch, etc.), neck (e.g., a necklace, etc.),head (e.g., a headband, hat, etc.), chest, or the like.

FIG. 2A is a block diagram of an example embodiment of a reader device120 in the form of a smartphone. Here, reader device 120 includes aninput component 121, display 122, and processing hardware 206, which caninclude one or more processors, microprocessors, controllers, and/ormicrocontrollers, each of which can be a discrete chip or distributedamongst (and a portion of) a number of different chips. Processinghardware 206 includes a communications processor 202 having on-boardmemory 203 and an applications processor 204 having on-board memory 205.Reader device 120 further includes an RF transceiver 208 coupled with anRF antenna 209, a memory 210, NFC communication circuitry 207 coupledwith antenna 217, Bluetooth communication circuitry 219 coupled withantenna 220, multi-functional circuitry 212 with one or more associatedantennas 214, a power supply 216, and power management circuitry 218.FIG. 2A is an abbreviated representation of the internal components of asmartphone, and other hardware and functionality (e.g., codecs, drivers,glue logic, etc.) can, of course, be included.

Communications processor 202 can interface with RF transceiver 208 andperform analog-to-digital conversions, encoding and decoding, digitalsignal processing and other functions that facilitate the conversion ofvoice, video, and data signals into a format (e.g., in-phase andquadrature) suitable for provision to RF transceiver 208, which can thentransmit the signals wirelessly. Communications processor 202 can alsointerface with RF transceiver 208 to perform the reverse functionsnecessary to receive a wireless transmission and convert it into digitaldata, voice, and video.

Applications processor 204 can be adapted to execute the operatingsystem and any software applications that reside on reader device 120,process video and graphics, and perform those other functions notrelated to the processing of communications transmitted and receivedover RF antenna 209, such as the handling and formatting of NFC orBluetooth communications. Any number of applications can be running onreader device 120 at any one time, and will typically include one ormore applications that are related to a diabetes monitoring regime, inaddition to the other commonly used applications, e.g., email, calendar,etc.

Memory 210 can be shared by one or more of the various functional unitspresent within reader device 120, or can be distributed amongst two ormore of them (e.g., as separate memories present within differentchips). Memory 210 can also be a separate chip of its own. Memory 210 isnon-transitory, and can be volatile (e.g., RAM, etc.) and/ornon-volatile memory (e.g., ROM, flash memory, F-RAM, etc.).

NFC communication circuitry 207 can be implemented as one or more chipsand/or components that perform controller functions (e.g., level anddata mode detection, framing, etc.), analog-digital conversions (ADC andDAC), and analog interfacing with antenna 217 (e.g., the modulation anddemodulation of NFC communications). Circuitry 207 can include avoltage-controlled oscillator (VCO), phase-locked loop (PLL) circuitry,a power amplifier for sending communications, and associated filters forwaveform shaping. Antenna 217 can be implemented as a loop-inductor asis typical for NFC platforms.

Similarly, Bluetooth communication circuitry 219 can be implemented asone or more chips and/or components that perform controller functions(e.g., level and data mode detection, framing, etc.), analog-digitalconversions (ADC and DAC), and analog interfacing with antenna 220(e.g., modulation and demodulation). Bluetooth communication circuitry219 can be configured to operate according to any of the Bluetoothstandards described herein. Circuitry 219 can include avoltage-controlled oscillator (VCO), phase-locked loop (PLL) circuitry,a power amplifier for sending communications, and associated filters forwaveform shaping.

Multi-functional circuitry 212 can also be implemented as one or morechips and/or components, including communication circuitry, that performfunctions such as handling other local wireless communications (e.g.,Wi-Fi) and determining the geographic position of reader device 120(e.g., global positioning system (GPS) hardware). One or more otherantennas 214 are associated with multi-functional circuitry 212 asneeded. Reader device 120 can include all of NFC communication circuitry207, Bluetooth communication circuitry 219, and multifunctionalcircuitry 212, or omit any one or more of those blocks (and associatedantennas) as desired for the individual application, so long as a mannerfor communicating with sensor control device 102 is maintained.

Power source 216 can include one or more batteries, which can berechargeable or single-use disposable batteries. Power managementcircuitry 218 can regulate battery charging and perform power sourcemonitoring, boost power, perform DC conversions, and the like.

Structural and functional components similar to that described withrespect to FIG. 2A can be present in reader device 120 in its otherforms as well (e.g., as a dedicated use device, tablet, wearable device,and others). Additional examples of reader device 120 configured as adedicated use device are described in the incorporated U.S. ProvisionalApplication No. 61/817,839 and the '225 Publication.

FIG. 2B is a block diagram depicting an example embodiment of sensorcontrol device 102 having analyte sensor 104 and sensor electronics 250(including analyte monitoring circuitry). Although any number of chipscan be used, here the majority of sensor electronics 250 areincorporated on a single semiconductor chip 251 that can be a customapplication specific integrated circuit (ASIC). Shown within ASIC 251are certain high-level functional units, including an analog front end(AFE) 252, power management (or control) circuitry 254, processor 256,and communication circuitry 258 for communications between device 102and reader device 120. In this embodiment, both AFE 252 and processor256 are used as analyte monitoring circuitry, but in other embodimentseither circuit (or a portion thereof) can perform the analyte monitoringfunction. Processor 256 can include one or more processors,microprocessors, controllers, and/or microcontrollers.

A non-transitory memory 253 is also included within ASIC 251 and can beshared by the various functional units present within ASIC 251, or canbe distributed amongst two or more of them. Memory 253 can be volatileand/or non-volatile memory. In this embodiment, ASIC 251 is coupled withpower source 260, e.g., a coin cell battery. AFE 252 interfaces with invivo analyte sensor 104 and receives measurement data therefrom,conditions the data signal, and outputs the data signal to processor 256in analog form, which in turn uses an analog-to-digital converter (ADC)to convert the data to digital form (not shown) and then processes thedata to arrive at the end-result analyte discrete and trend values, etc.

This data can then be provided to communication circuitry 258 forsending, by way of antenna 261, to reader device 120 (not shown) wherefurther processing can be performed. Communication circuitry 258 canoperate according to any of the NFC, Bluetooth, and Wi-Fi communicationprotocols described herein, or any other desired communication protocol,depending on the selected manner of communication with reader device120. For example, communication circuitry 258 can include functional anddiscrete components similar to those of NFC communication circuitry 207or Bluetooth communication circuitry 219 described with respect to FIG.2A.

FIG. 2C is similar to FIG. 2B but instead includes two discretesemiconductor chips 262 and 263, which can be packaged together orseparately. Here, AFE 252 is resident on ASIC 262. Processor 256 isintegrated with power management circuitry 254 and communicationcircuitry 258 on chip 263. In one example embodiment, AFE 252 iscombined with power management circuitry 254 and processor 256 on onechip, while communication circuitry 258 is on a separate chip. Inanother example embodiment, both AFE 252 and communication circuitry 258are on one chip, and processor 256 and power management circuitry 254are on another chip. Other chip combinations are possible, includingthree or more chips, each bearing responsibility for the separatefunctions described, or sharing one or more functions for fail-saferedundancy.

Incorporation of the majority, or all, of the data processing intosensor control device 102 allows reader device 120 to act mostly orentirely as a display and interface device for the user. This canprovide an advantage in managing regulatory approval of system 100, assensitive glucose calculations and related processing can be performedon the sensor control device 102 and not on an uncontrolled dataprocessing device such as a commercially available smartphone.Conversion of a smartphone, or other similar commercially availabledevice, into reader device 120 suitable for interfacing with sensorcontrol device 102 can be accomplished by installing a softwareapplication (or “app”) onto the smartphone in a conventional mannerwithout any hardware additions or modifications. The softwareapplication need only interface with the appropriate communicationcircuitry (e.g., 207, 219, 212) on this smartphone to accept and displaythe end-result data from sensor control device 102 (glucose data, trenddata, etc.).

The incorporation of algorithmic data processing within sensor controldevice 102, along with the use of a continuous wireless transmissionprotocol can also provide the advantage of allowing sensor controldevice 102 to readily interface with products provided by third partiesor other manufacturers, such as other types of healthcare systems thatdo not have the on-board glucose data processing capabilities and/oralgorithms. Examples of third party systems include continuous glucosemonitoring systems, home health monitoring systems, hospital vital signmonitors, and closed loop systems (such as an artificial pancreas), orinsulin pumps, and the like.

However, the data processing functions described herein can take placewithin the sensor control device 102 (as just described), reader device120, computer system 170, or any combination thereof. This can includedeterminations of the user's analyte or glucose value, determinations ofthe variation or fluctuation of the monitored analyte level as afunction of time, determinations of glucose trend over time,determinations of glucose rate of change, the occurrence of an alarmcondition such as hypoglycemia or hyperglycemia or impendinghypoglycemia or hyperglycemia, and any other data processing functionsdescribed herein (or with respect to data processing module 160 in the'225 Publication).

Example Embodiments for Changing the Power State Using External StimuliSuch as Optical or Magnetic Energy

As described earlier, after the completion of the manufacturing processthere may be an extended period of time during which system 100 is notused, for instance, while awaiting shipment, while being present “on theshelf,” or while otherwise awaiting initial use by the customer orsubject. During this time, sensor control device 102 may use minimalpower in order to conserve the life of on-board power source 260. Sensorcontrol device 102 may be in a low power state, or altogetherdeactivated if power source 260 is electrically isolated from theremainder of sensor electronics 250. Embodiments where thepost-manufacturing initialization, or activation, is performed usingwireless signals are described in the incorporated ProvisionalApplication No. 61/817,839. The following embodiments can be freelysubstituted for those wireless-based embodiments.

FIG. 3 is a block schematic view depicting an example embodiment ofsensor electronics 250 having an activation circuit 301. Here,activation circuit 301 is shown interposed between power source 260 andseveral functional components of sensor electronics 250. Specifically,those functional components are shown as power management circuitry 254and processor 256, both of which are described with respect to FIGS.2B-C as components of either a one chip embodiment (residing within ASIC251) or a two chip embodiment (residing within chip 263), respectively.Therefore, the embodiment described with respect to FIG. 3 (and laterFIG. 7 ) is applicable to devices having one chip, two chips, or more.

In this embodiment, activation circuit 301 includes a P-type MOSFET(PMOS) 302, an N-type MOSFET (NMOS) 304, a resistor 306, and an opticalactivation sensor 308 (also referred to herein as “optical sensor 308”),which, in this example, is an optically activatable switch 308. Thepositive terminal of power source 260 is coupled with a first terminalof resistor 306 and a source node of PMOS 302. The gate node of PMOS 302is coupled with the opposite terminal of resistor 306, a drain node ofNMOS 304, and a first terminal of optically activatable switch 308. Thedrain node of PMOS 302 is coupled with power management circuitry 254,and the gate node of NMOS 304 is coupled with processor 256. Thenegative terminal of power source 260, the opposite terminal ofoptically activatable switch 308, and the source node of NMOS 304 areeach coupled with ground, or reference node, 312.

Optically activatable switch 308 is just one type of optical sensor.Optically activatable switch 308 can be any device that transitions froman open circuit (or current blocking state) to closed circuit (orcurrent passing state) upon the incidence of radiation in the opticalband (optical light). The larger field of optical sensors can includeany device that produces a physical, thermal, or electrical response tothe presence of optical light. Those of skill in the art will readilyrecognize that the response should be of sufficient magnitude todistinguish it from noise or other negligible responses. Other bands ofradio frequency can be used to activate the switch, includingultraviolet, infrared, and so forth. Optically activatable switch 308can be, for instance, a photodiode or phototransistor. Here, opticallyactivatable switch 308 is shown as a photodiode that transitions from anopen state (e.g., a low energy storage state in which current cannotflow) to a closed state (i.e., an active state in which current canflow) upon the receipt of sufficient optical radiation 310. In manyembodiments, the amount of optical radiation 310 necessary to activateswitch 308 is relatively low to ensure easy activation by the user atthe appropriate time.

Upon receipt of a sufficient amount of radiation 310, photodiode 308permits current to flow through resistor 306, which in turn causes thegate bias on PMOS pass transistor 302 to drop, thereby allowing currentto flow from power source 260 to power management circuitry 254. Powermanagement circuitry 254 is in communication with processor 256 andprovides one or more commands or signals to processor 256 to initiate,or boot up, at which point processor 256 can perform an activationroutine for sensor control device 102 that brings the remaining sensorelectronics 250 into a higher power state.

This technique, as implemented in the optical, magnetic, and otherembodiments herein, provides a significant advantage over conventionalactivation approaches. One such approach is that described in US PatentPubl. 2012/0078071 (Bohm et al.) where a processor must remain active,either by staying awake in a low-power mode or by being awoken inrepeated fashion (e.g., each minute), in order to monitor for aninterrupt signal (or other indicator) that the sensor device is ready tobe taken out of a storage or other inactive mode. During these instanceswhere the processor is in an active mode, even if the mode is a lowpower one, or only occurs for short intervals, the processor isfunctioning and drawing current from the power source at a greater rate,thereby depleting the stored charge of the power source and lesseningthe shelf life of the sensor device. This and other disadvantages areovercome with the embodiments described herein.

In certain embodiments, microprocessor 256 is capable of applying (andholding) a gate bias voltage to the gate of NMOS pass transistor 304 inorder to allow current to flow across transistor 304 and thereby latchPMOS 302 in the “ON” state. Stated differently, processor 256 is capableof bypassing the optical sensor after changing the power state of device102. Thus, should the light incident on the optical sensor (e.g.,photodiode 308) become interrupted, sensor electronics 250 will remainactive.

In many embodiments, optically activatable switch 308 operates with arelatively low dark current, for example, on the order of 10 nanoamps(nA) or less, so that switch 308 will not significantly impact the lifeof power source 260 during storage.

Although this embodiment has been described with respect to MOSFETdevices, those of ordinary skill in the art will readily recognize thatany number of other transistor types can be substituted for thosedescribed here, while achieving the same practical result. Also, in viewof the disclosure contained herein and the schematic depicted in FIG. 3, those of ordinary skill in the art will readily recognize a number ofother circuit designs that can take advantage of an optical sensor 308to achieve the same or similar result. The existence of power managementcircuitry 254 as a separate functional component is optional as thisfunction can be embedded within processor 256.

Still further, the components of activation circuit 301 can beimplemented “on-chip” or “off-chip” or any combination thereof. (On-chiprefers to the integration of the respective component with all othercomponents on one semiconductor die.) Here, each of the components ofactivation circuit 301 is located on-chip with the exception ofoptically activatable switch 308, which is located off-chip. Theplacement of optically activatable switch 308 off-chip allowsflexibility in the overall package design for sensor electronics 250,for example, by allowing optically activatable switch 308 to be placedin a location amenable to the receipt of sufficient light at the desiredactivation time.

Optical sensor 308 can be located within a housing of sensor controldevice 102, on the outer surface of sensor control device 102, or in aposition coupled with the applicator (where it would later becomedetached upon deployment of sensor control device 102), so long asoptical sensor 308 remains communicatively coupled with sensorelectronics 250 so as to permit activation of those electronics.

FIG. 4 is a flowchart depicting an example method 400 of using anoptically activatable embodiment of system 100. FIG. 4 will be describedin conjunction with the sequential diagrams of FIGS. 5A-G. A user 500 isdepicted in FIG. 5A with example application sites 502 and 504. In someembodiments, other application sites may be used and a site preparationoperation may optionally be performed. At 402 (FIG. 4 ), user 200 startswith unpacking a sensor container 506, such as is depicted in FIG. 5B.Container 506 can include a casing 510 which, in this embodiment, holdsthe sensor itself and an insertion sharp (or in some embodiments, theelectronics assembly for controlling the sensor itself). Unpackingcontainer 506 can include removing a container cover 508 that provides asterile seal to the container contents.

At 404 (FIG. 4 ), user 200 unpacks an applicator 512, which can includeremoving an applicator cover 514 (e.g., an end cap) that provides asterile seal to the internal portion of an applicator assembly 516 asshown in FIGS. 5C-D. In this embodiment, the remainder of sensor controldevice 102, such as sensor electronics 250 and power source 216, as wellas an overall housing for sensor control device 102, are present(obscured here) within application assembly 516. In embodiments wherecontainer 506 holds sensor electronics 250 in one assembly, thenapplicator assembly 516 can hold the sensor itself and the insertionsharp as another assembly. One reason for separating the two assembliesis to allow each to undergo separate sterilization processes.

In some embodiments, container 506 and applicator 512 can initially bepackaged connected together to simplify packaging and shipping. Thus, inthose embodiments, before removing cover 508 from the casing 510 andseparating removable end cap 514 from applicator assembly 516, in aninitial unpacking step, container 506 and applicator 512 are separatedfrom each other.

At 405 (FIG. 4 ), user 500 exposes sensor control device 102 to ambientlight, or a light bulb, LED, or other light source, in order to initiateoptical sensor 308 (e.g., an optically activatable switch) containedwithin sensor control device 102. At this point, sensor electronics 250become activated and sensor control device 102 can begin communicationwith reader device 120. Step 405 can be a positive step, such as theuser physically directing the light-sensitive optical sensor 308 towardsthe light source. Step 405 can also be a direct result of removal of theapplicator cover in step 404, in which case ambient light canimmediately propagate into applicator assembly 516 as depicted by thedashed arrows of FIG. 5D, and impinge upon optical sensor 308, in aconfiguration such as that described with respect to FIG. 12C. Inanother embodiment, optical sensor 308 can be covered by a door, patch,sticker, or other opaque structure, and exposure to the requisite amountof light occurs by removal of that door, patch, sticker, or other opaquestructure.

At 406 (FIG. 4 ), the initialization, or activation, of sensorelectronics 250 is verified. This can be performed automatically bysensor control device 102 or reader device 120. For instance, in oneembodiment a successful initialization of sensor electronics 250 willenable communications to be transmitted from sensor control device 102to reader device 120, at which point reader device 120 can generate anindication or message to the user that sensor electronics 250 weresuccessfully activated. In another embodiment a visual, auditory,vibrational, or tactile output is generated by sensor control device 102that indicates successful activation to the user.

Next, in an assembly operation 407 (FIG. 4 ), applicator 512 is insertedinto container 506 to merge or connect the sensor assembly and thesensor electronics assembly together to form sensor control device 102and an insertion needle or sharp. As shown in FIG. 5E, oncecorresponding alignment indicators 518 and 520 are aligned, a first partof the user assembly operation 407 is carried out by pushing applicatorassembly 516 firmly into container 506 to retrieve a sensor and a sharpfrom container 506 and to unlock a guide sleeve of applicator assembly516. Applicator assembly 516 is then removed with the sensor and sharpfrom container 506, as shown in FIG. 5F.

Next, once the user has chosen an application site, a sensor controldevice application operation 408 (FIG. 4 ) is performed. User 500 placesapplicator assembly 516 on the skin of the insertion site 504 and thenapplies an uncontrolled force to install sensor control device 102, asshown in FIG. 5G. Applicator 516 is manually pushed to insert the distalend of the sensor itself through the user's skin and to adhere sensorcontrol device 102 to the skin surface. The sharp can be automaticallyretracted into applicator assembly 516 for disposal, at which pointapplicator assembly 516 can be manually removed from site 504, as shownin FIG. 5H.

In some embodiments, user 500 performs application operation 408 byapplying an uncontrolled force to applicator assembly 516 where theuncontrolled force is applied in a single, continuous pushing motionalong the longitudinal axis of applicator assembly 516 that oncestarted, causes applicator assembly 516 to perform the applicationoperation 408 such that applicator assembly 516 does not stop operationuntil completion. Applicator assembly 516 can be configured to relayaction/audible cues to user so 500 that all three of the above listedactions happen automatically in response to applying the force to theapplicator causing it to trigger.

Advantageously, an adhesive of sensor control device 102 does notcontact the user until the downward travel of applicator assembly 516has completed. So, even after applicator assembly 516 has been placed onthe skin, it can be moved to a different location as many times asdesired until application operation 408 is actually carried out, andthis is without damage to the apparatus or other system components. In apost-application stage 410, use of sensor control device 102 formonitoring the user's analyte level occurs during wear followed byappropriate disposal. An example of such a stage is depicted in FIG. 5I,where analyte levels detected by the sensor of sensor control device 102can be retrieved over a wireless communication link 140 via a readerdevice 120. Relevant information (e.g., analyte level trend data,graphs, etc.) is presented on the reader device's display 122.

Steps 405 (light exposure) and 406 (initialization) were described aboveas being performed prior to step 407, however, in some embodiments steps405 and 406 are performed after step 407, and in other embodiments steps405 and 406 are performed after step 408. Also, step 406 can beperformed immediately after step 405 or with one or more interveningsteps.

Additional details regarding the method steps described with respect toFIGS. 4 and 5A-I can be found in the incorporated U.S. ProvisionalApplication No. 61/817,839.

Applicator 512, container 506, and the associated components shown inFIGS. 5A-I are illustrated in more detail in FIGS. 6A and 6B. Inaddition, numerous other variations are described in detail below. Thesealternative embodiments may operate differently insofar as theirinternal workings, but may present no difference concerning useractivity.

Turning to FIG. 6A, applicator 512 includes a removable cap 514 (a typeof cover) and applicator assembly 516. Removable cap 514 can be securedto applicator assembly 516 via complementary threads 606 and 606′. EndCap 514 fits with applicator assembly 516 to create a sterile packagingfor the applicator interior. Therefore, no additional packaging isrequired to maintain sterility of the interior of applicator assembly516.

In some embodiments, the end (not visible) of removable end cap 514 caninclude one or more openings, which can be sealed by a sterile barriermaterial such as DuPont™ Tyvek®, or other suitable material, to formseal 608. Such provision allows for ethylene oxide (ETO) sterilizationof the applicator 512 through seal 608 when closed. In some embodiments,the openings in removable cap 514 may not be present and removable cap514 may be made from a sterile process-permeable material so that theinterior of applicator assembly 516 can be sterilized when cap 514 ismated to it, but that maintains sterility of the interior of the capafter exposure to the sterility process. In some embodiments, ETOsterilization is compatible with the electronics within sensorelectronics 250 and with the associated adhesive patch 105, both ofwhich can be releasably retained within applicator assembly 516 untilapplied to the user. As shown, applicator assembly 516 includes ahousing 614 including integrally formed grip features 616 and atranslating sheath or guide sleeve 618.

In reference to FIG. 6B, container 506 includes a cover 508 (e.g., madeof a removable material such as foil) and casing 510. Housed withincasing 510 is a desiccant body 612 and a table or platform 608. A sensorassembly 610 is snap-fit or otherwise held by the sensor assemblysupport 613. Sensor assembly 610 can also be snap-fit or otherwise heldby the platform 608 (e.g., using fingers). With cover 508 sealed,container 510 can be subjected to gamma or radiation (e.g., e-beam)sterilization, an approach compatible with the chemistry of the sensorincluded in sensor assembly 610. Like applicator 512, container 506 isits own sterile packaging so that no additional packaging, other thancasing 510 and cover 508, is required to maintain sterility of theinterior of the casing.

In addition to optical manners of activation, other types of activationcan be used with sensor control device 102. One such example is magneticactivation. FIG. 7 is a block schematic diagram depicting an exampleembodiment of sensor electronics 250 configured to be magneticallyactivatable. Here, activation circuit 701 is essentially the same asthat depicted in FIG. 3 (and has the same advantages as those describedwith respect to FIG. 3 ) except that optically activatable switch 308 isreplaced with a magnetic activation sensor 702 (also referred to hereinas “magnetic sensor 702”), which in this embodiment is a magneticallyactivatable switch. Magnetic sensor 702 can be any device that producesa measurable output in response to the presence of a magnetic field 704.Magnetically activatable switch 702 can be any switch that willtransition from a closed to open state upon the application of asufficient magnetic field 704, or any device that will generate currentflow to bias a pass transistor in activation circuit 701 uponapplication of a sufficient magnetic field 704. FIG. 7 showsmagnetically activatable switch 702 as a Reed switch, but other staticdevices can be used such as a Hall effect sensor, and the like, or otherdynamic devices.

The operation of the embodiment in FIG. 7 is essentially the same asdescribed with respect to FIG. 3 except that instead of the applicationof sufficient light, the application of a sufficient magnetic field 704causes magnetically activatable switch 702 to transition from an openstate to a closed state that permits current to flow through resistor306. Magnetic field 704 can be applied by bringing a permanent ortime-varying magnet into proximity with magnetically activatable switch702. For instance, system 100 can be provided to the user with apermanent magnet that is stored in the packaging of activator assembly516 at a distance sufficient to prevent activation until the userphysically brings the magnet into close proximity with switch 702.Alternatively, the magnet can be provided in separate packaging, and soforth.

Magnetic sensor 702 can be located within a housing of sensor controldevice 102, on the outer surface of sensor control device 102, or in aposition coupled with applicator 512, so long as magnetic sensor 702remains communicatively coupled with sensor electronics 250 so as topermit activation of those electronics 250.

FIG. 8 is a flowchart depicting an example method 800 of using amagnetically activatable embodiment of system 100. Many of the stepsdescribed here are the same as those described with respect to FIG. 4 ,so some common details will not be repeated. A user starts withunpacking container 506 at 802 and unpacking applicator 512 at 804.Unpacking container 506 at 802 can include removing cover 510 thatprovides a sterile seal to the container contents. Unpacking applicator512 at 804 can include removing end cap 514 that provides a sterile sealto the internal portion of applicator assembly 516.

At 805, the user exposes sensor control device 102 to a magnetic field,for example, by bringing sensor control device 102 and/or a magnet intoclose proximity with each other, in order to initiate magnetic sensor702 contained within sensor control device 102. At this point, sensorelectronics 110 become activated and sensor control device 102 can begincommunication with reader device 120. It should be noted that step 805can be a positive step, such as the user physically bringing themagnetically-sensitive region of applicator 512 towards the source ofthe magnetic field (or vice versa), or step 805 can be a direct resultof removal of applicator cover 514, such as by removal of a magneticfield supplied by a magnet in or on cover 514, which in turn causesactivation of electronics 250.

At 806, the initialization, or activation, of sensor electronics 250 isverified. This can be performed automatically by communication betweensensor control device 102 and reader device 120. For instance, in oneembodiment a successful initialization of sensor electronics 250 willenable a communication to be transmitted from sensor control device 102to reader device 120, at which point reader device 120 can generate anindication or message to the user that sensor electronics 250 weresuccessfully activated. In another embodiment a visual, auditory,vibrational, or tactile output is generated by sensor control device 102that indicates successful activation to the user.

The method of use can proceed with steps 807, 808, and 810 in the samemanner as described with respect to FIG. 4 . Steps 805 (exposure) and806 (initialization) were described above as being performed prior tostep 807, however, in some embodiments steps 805 and 806 are performedafter step 807, and in other embodiments steps 805 and 806 are performedafter step 808. Also, step 806 can be performed immediately after step805 or with one or more intervening steps.

Other examples of manners of initialization include the use of nearfield communication (NFC), cellular energy, Bluetooth energy, Wi-Fienergy, and the like. These types of RF energy can be applied bydedicated devices sold with system 100, or by commercially availabledevices that can be integrated by the user into system 100, for example,a smartphone or tablet.

In one embodiment, placement of sensor control device 102 into proximitywith the user's skin or body will be sensed by a temperature sensitivedevice that can be used to activate sensor electronics 250. Thetemperature sensitive device can be a differential device that candistinguish the body temperature of the user from what could be arelatively high ambient temperature. Upon detection of a sufficientgradient between the ambient temperature and the temperature of theuser's body (expected to be a typical human body temperature), thetemperature sensitive device will become enabled and activate operationof electronics 250, such as by closing a circuit to the power source.

Alternatively, a mechanical switch can be present on device 102, theactuation of which initiates electronics 250 therein. In yet anotheralternative embodiment, a shorting bar or shorting path can be used. Forexample, sensor assembly 610 (FIG. 6B) can have a conductive path eitherentirely exposed or with at least two exposed surfaces. Sensor controldevice 102 can have exposed leads, where the gap between the leads is anopen circuit that prevents the supply of power from the power source orbattery to the remainder of electronics 250. When sensor assembly 610 isbrought into contact with the remaining portion of sensor control device102, the exposed leads on device 102 come into contact with exposedportions of the conductive path on or in sensor assembly 610. Theexposed leads on device 102 are then shorted together by the conductivepath of sensor assembly 610, thereby activating electronics 250.

The construction of an example embodiment of sensor control device 102described with respect to the following FIGS. 9A-12C is similar to thatdescribed in U.S. patent application Ser. No. 13/710,460, filed Dec. 11,2012, and U.S. Provisional Application No. 61/569,287, filed Dec. 11,2011, both of which are incorporated by reference herein for allpurposes. In the present description, sensor control device 102 isdescribed with features that facilitate optical activation.

FIGS. 9A-D provide top (FIG. 9A) and bottom (FIGS. 9B-D) constructionviews of an example sensor control device subassembly. A socket 902 ormount is fit through vias in a printed circuit board 900 along withother associated components including a processor 904 (e.g., an ASICincluding a communications facility), thermistor/thermocouple 906, abattery mount 908, optical sensor 308, etc. Once circuit board 900 hasbeen populated with these components, socket 902 is adhered to circuitboard 900 (e.g., using heat stakes) as shown in FIGS. 9C-D. Once battery260 is set in place, circuit board 900 as shown in FIG. 9E is preparedfor incorporation into sensor control device 102.

Circuit board 900 is ready for an over-mold process or other sealingmethod. As illustrated in FIGS. 10A-D, circuit board 900 is first set ina two-piece mold 1002, 1004. A mold slide 1006 is inserted and mold1002, 1004 is closed as shown in FIG. 10B. As depicted in FIG. 10C, athermoplastic material is injected into the mold 1002, 1004, encasingcircuit board 900. Mold 1002, 1004 is opened and the near-final partejected as shown in FIG. 10D.

Alternatively, the enclosure of the electronics assembly of sensorcontrol device 102 may include elements snap-fit (or welded/adhered)together as illustrated in the assembly view of FIG. 11A, theas-assembled view of FIG. 11B, and in cross-sectional perspective viewof FIG. 11C. An enclosure including a top shell 1102 and a mounting base1104 can be used to sealably enclose and protect circuit board 900. Topshell 1102 (or whatever portion of the housing is opposite opticalsensor 308) is preferably transparent, or semi-transparent, to let lightpass therethrough so as to permit the light to be incident upon andactivate optical sensor 308 (not shown).

When snap-fit, various interference or snap fit elements (e.g., annularrims 1106) may be provided around the entirety of the periphery of theenclosure or as discrete snap-fit connectors (not shown). Notably, suchan approach may benefit from additional O-ring sealing elements to avoidfluid intrusion. Alternatively or additionally, adhesive set at the snapjunction(s) may be used to ensure good sealing, especially in connectionwith continuous annular snap-fit features 1106. As seen in FIG. 11C, atrough 1108 or other features can be provided to ensure that adhesive1110 that may be squeezed out during assembly is not forced into areasthat could interfere with operation or assembly of sensor control device102. In some embodiments, when top shell 1102 and mounting base 1104 arefit together with a bead of adhesive 1110 in place as shown, trough 1108not only provides space to capture adhesive 1110 squeezed out but alsoprovides additional surface area for a thicker layer of adhesive 1110 toseal the joint. While the entire top shell 1102 can be adapted to permitthe passage of light, in an alternative embodiment only portion 1116immediately adjacent to optical sensor 308 (not shown) is transparent orsemi-transparent (e.g., translucent).

However constructed, final assembly of the electronics assembly ofsensor control device 102 involves adhesive patch installation. Anexemplary approach is illustrated in FIGS. 12A-C. First, a double-sidedadhesive patch 1204 has the inner liner 1202 removed. This exposedadhesive is set over a sensor control device body 1206 (with thetemperature sensor 906 folded to seat within a complementary pocket) andadhered with a first window 1208 aligned for temperature sensing, asecond window 1210 for sensor assembly receipt, and a third window 1218aligned with the portion 1116 of shell 1102 immediately adjacent tooptical sensor 308 (not shown). The surface of sensor control device 102facing the user is substantially covered with adhesive except for theaforementioned windows. As such, it is ready for placement in anapplicator assembly upon removal of the outer release liner, oralternatively ready for placement in a container with or without theouter liner in place, depending on the presence or absence of anyliner-puller features provided therein.

The surface of sensor control device 102 on which window 1218 is located(as shown in FIG. 12C) faces the end cap when the applicator is in itssterile and packaged state. Thus, removal of the end cap immediatelyexposes window 1218 to the ambient light, causing initialization oractivation of sensor control device 102 with little or no extra effortor steps by the user.

Example Embodiments for Changing the Power State Using WirelessTransmissions

Additional embodiments that can be used to activate sensor controldevice 102, establish communication with sensor control device 102,and/or reestablish communication with sensor control device 102 (e.g.,after a prior communication session has ended) are set forth here. Theseembodiments involve the sending of one or more RF transmissions fromreader device 120 to sensor control device 102. In some embodiments, theRF transmissions are sent according to a Bluetooth protocol in the RFband from about 2400 to 2480 Megahertz (Mhz) (or 2.4 to 2.48 Gigahertz(Ghz)), while in other embodiments communications made according to NFCprotocols and other protocols and frequency bands can also be utilized.

As already mentioned, sensor control device 102 is provided to the userin a powered-off (or power-off, or deactivated) state where thecircuitry of sensor control device 102 consumes little, if any, currentfrom power source 210. Sensor control device 102 can be activated suchthat it changes state from this powered-off (or storage) state to asecond state that consumes relatively higher power.

If in the storage state, the second state may be a normal operationstate. If in a fully deactivated powered-off state, the second state maybe characterized as a low-power state that is used to conduct low-powermonitoring for wireless signals or transmissions coming from readerdevice 120. These transmissions can advertise the availability of readerdevice 120 to establish a communication session with sensor controldevice 102. The transmission(s) can be used to activate sensor controldevice 102. This low-power state can allow sensor control device 102 tooperate for a relatively long period of time while device 102 awaits thereceipt of a wireless transmission from reader device 120.

Once sensor control device 102 receives one or more wirelesstransmissions from reader device 120 that indicate that the user isready to begin normal usage of sensor control device 102 (e.g., thecollection and transmission of sensed analyte data), then sensor controldevice 102 can optionally transition to a third state that consumes evenhigher power than the first (e.g., fully deactivated) and second states.In this third state, sensor control device 102 can fully establish thecommunication link with reader device 120, sense analyte levels in theuser's bodily fluid, perform some degree of processing on the senseddata, and/or transmit that sensed data to the reader device 120.Continuous operation in this third state will, in most embodiments, lastfor a predetermined time period, e.g., 14 days.

Of course, in any of the embodiments described herein, it is possiblefor sensor control device 102 to temporarily enter lower power states toconserve energy even after commencement of normal operation.

Sensor control device 102 can be activated using wireless RFtransmissions, e.g., can transition from a powered-off state, or astorage state, to a higher power state, at any time prior tocommunicating with reader device 120. For example, sensor control device102 can be wirelessly activated before removal from its packaging, uponremoval from its packaging, after removal from its packaging but priorto application to the user's body, upon application to the user's body,or after application to the user's body.

FIG. 13 is a block diagram that will be used to describe exampleembodiments of a method 1300 of establishing communication betweensensor control device 102 and reader device 120 using a Bluetoothprotocol. These embodiments can also be used to activate sensor controldevice 102 or otherwise place sensor control device 102 in a higherpower state. These embodiments can further be used to re-establishcommunication between sensor control device 102 and the same or adifferent reader device 120 with which sensor control device 102 hadpreviously been communicating.

At 1302, sensor control device 102 is applied to the body of a user suchthat the adhesive patch is satisfactorily adhered to the user's skinwith sensor 104 extending into tissue and in contact with bodily fluid(e.g., ISF, dermal fluid, and the like). At this point, it is desirablefor sensor control device 102 to monitor for one or more wirelesstransmissions from reader device 120. Sensor control device 102 can bein either a power-off state or a low-power state, such as a sleep state,that consumes less power than the normal operation state.

If sensor control device 102 is in a powered-off state, then that stateshould be capable of supplying at least a minimal amount of current tocommunication circuitry 258 (operating according to the appropriateBluetooth protocol) to allow monitoring for a wireless transmission fromreader device 120. Accordingly, communication circuitry 258 can have alow-power function or state that consumes less power than the normalstate of operation, and this low-power state can be used for monitoringfor a first wireless transmission from reader device 120.

If the powered-off state is not capable of supplying sufficient currentfor monitoring for a wireless transmission because, for example, thepower source is electrically disconnected, then sensor control device102 is transitioned from the powered-off state to a low-power statewhere monitoring is possible. In some embodiments, the powered-off orthe low-power state of sensor control device 102 does not permit thetransmission of messages in order to save power.

At 1304, reader device 120 is activated (if not already) and the userinitiates connection with sensor control device 102 by, for example,selecting an option to do so on the user interface of reader device 120.At 1306, the user brings reader device 120 into close proximity (e.g.,less than 6 feet, less than 3 feet, less than 2 feet, less than 1 foot,or less than 6 inches, etc.) with sensor control device 102, if readerdevice 120 is not already in such a position.

In these embodiments, the initiation of a connection at step 1304 causesreader device 120 to begin sending wireless transmissions according to aBluetooth protocol. In some of these embodiments, the wirelesstransmissions are sent in accordance with an advertising regimen of theBTLE protocol, and transmitted at the highest power level allowable byreader device 120. The advertising regimen is a link layer mode of BTLE,and is typically carried out while reader device 120 is in anadvertising state by the performance of an advertising event, which caninclude the sending of one or more advertising request packets on one ormore advertising channels (e.g., one, two, or three) of the link layerof the BTLE packet structure (e.g., protocol data unit (PDU) header, PDUpayload, CRC). Each packet can be sent on each advertising channel at aspecified time interval.

Each advertising packet can contain an advertising request, which is apredetermined string of bits, or bit code, that can be interpreted bysensor control device 102 as a request to initiate the communicationsession. An example of an advertising request is a packet data unit(PDU) type corresponding to a connectable directed advertising event(ADV_DIRECT_IND). ADV_DIRECT_IND is described in the incorporatedBluetooth specification, version 4.0, as a 0001 code appearing in the 4most least significant bits (the PDU type) of the PDU header. In certainembodiments, for the connectable directed advertising packet, the timeinterval between the sending of consecutive requests on the same channelis 3.75 milliseconds (ms) or less, and these repeated transmissions canpersist for a predetermined length of time, e.g., as long as about 1.28seconds (s). If sent on two advertising channels provided by BTLE, theinterval between consecutive requests on any channel will be about 1.375ms or less and, if sent on three channels, the interval will be about1.25 ms or less.

Other PDUs can be used as well, such as: ADV_IND, which can be a 0000code corresponding to a connectable undirected event; ADV_NONCONN_IND,which can be a 0010 code corresponding to a non-connectable undirectedevent; and ADV_SCAN_IND, which can be a 0110 code corresponding to ascannable undirected event.

At 1307, sensor control device 102 detects the advertising message orsequence and, at 1308, demodulates the transmission to determine if anactivation request is present. The determination of whether anactivation request is present can be performed by processor 256 orcommunication circuitry 258 (e.g., a BTLE transceiver). If theactivation request is present, sensor control device 102 can transmit anactivation confirmation message at 1310. The activation confirmationmessage can be a predetermined bit code that is recognized by readerdevice 120 as confirmation that sensor control device 102 is ready toestablish a connection. For example, the activation confirmation messagecan be a CONNECT_REQ (0101) or a SCAN_REQ (0011) PDU. In someembodiments, prior to transmitting the activation confirmation message,sensor control device 102 changes into a higher power mode of operation,such as a normal operation state, that enables the use of power totransmit messages. Upon receiving the activation confirmation message,reader device 120 can transition from the advertising state to theconnection state according to the BTLE protocol.

If the activation request is not present, then, at 1311, sensor controldevice 102 can continue to monitor for another transmission sentaccording to an advertising feature of the BTLE protocol. In someembodiments, sensor control device 102 can wait a predetermined periodof time, e.g., 2 to 3 seconds, before monitoring for anothertransmission.

The user continues to hold reader device 120 in close proximity withsensor control device 102 until reader device 120 indicates, at 1312,that a connection is being established or has been established. Thisindication can be a visual indication on a display of reader device 120,an audible indication (e.g., a beep, tone, jingle, etc.), a tactileindication (e.g., a vibration or series of vibrations), or anycombination thereof. Reader device 120 can provide such an indicationupon receiving the activation confirmation message from sensor controldevice 102. Reader device 120 and sensor control device 102 can thenproceed with formally establishing a communication link or pairing andcan begin the exchange of analyte data sensed from the body of the user.

FIG. 14 is a block diagram that will be used to describe additionalexample embodiments of a method 1400 of establishing a communicationlink between sensor control device 102 and reader device 120. Theseembodiments are similar to those embodiments described with respect toFIG. 13 , and therefore many of the common aspects will not be repeated,with the attention instead focusing on those aspects that differ.

At 1402, sensor control device 102 is placed in, or transitions to, alow-power receiving mode or state. As already stated herein, sensorcontrol device 102 can be shipped in this state, or can be shipped in afully powered-off state and transitioned into this state by the user,e.g., manually with a switch or other actuator, or automatically with aphoto-sensor or magnetic sensor, etc.

At 1403, sensor control device 102 monitors for a Bluetooth transmissionand, if one is received, determines if that transmission qualifies as anadvertising message or sequence at 1404. This determination can beaccomplished without demodulating the wireless transmission, and can beperformed by processor 256 or communication circuitry 258. For example,if a sequence of two or more transmissions are received at theappropriate time interval (e.g., less than or equal to 3.75 ms) and atthe appropriate frequency (e.g., approximately 2.4 Ghz), then processor256 can assume that the transmissions are part of a direct advertisingregimen according to the BTLE protocol. If the one or more transmissionsdo not qualify, then sensor control device 102 returns to monitoring foranother wireless transmission, optionally by first waiting thepredetermined period of time at 1405.

If the transmission or transmissions do qualify, then at 1406, processor256 (through its programming) transitions sensor control device 102 to ahigher power state that allows for the demodulation of one or morewireless transmissions and the sending of a response. This can be, forexample, a normal operation state of sensor control device 102. At 1408,the next, or a subsequent, wireless transmission is demodulated bysensor control device 102 (e.g., by BTLE transceiver 258). At 1410,sensor control device 102 determines if the demodulated transmissionincludes an activation request. If it does not, then sensor controldevice 102 can return to the low-power state at 1402 (either before orafter waiting an optional predetermined time at 1405), where it can thenproceed to monitor for new wireless transmissions.

If the demodulated transmission does include the activation request,then sensor control device 102 transmits the activation confirmationmessage at 1412. Sensor control device 102 and reader device 120 canthen proceed to finalize the pairing and/or otherwise continue withnormal operation at 1414.

In another example embodiment, reader device 120 transmits advertisingrequests as part of a connectable directed advertising event with amaximum power level allowable by the reader device 120, which can be asmart phone. Sensor control device 102 receives one or more of theserequests and changes state from a low power (e.g., storage) state to ahigher power state (e.g., normal operation). Sensor control device 102then begins advertising for a connection with reader device 120according to any advertising regimen in the BTLE protocol (e.g., anadvertising regimen that is not a connectable directed advertisingevent), and reader device 120 can receive the advertising requests andrespond accordingly. Thus, in this embodiment, both sensor controldevice 102 and reader device 120 act as advertisers at some point.Reader device 120 acts as an advertiser to wake up device 102, anddevice 102 then acts as an advertiser to establish a connection withreader device 120.

Turning now to other embodiments, in some cases, to accomplish aconnection of a power source in an electrical manner, another source ofpower may be required to operate the responsible circuitry. Embodimentsof the systems, devices, and methods described herein provide for, amongother things, the utilization of the power (or current) harnessed frommultiple wireless RF communications, e.g., NFC communications, sent fromreader device 120 to sensor control device 102 to drive the responsibleconnection circuitry. These multiple RF communications provide the powernecessary to connect the power source or otherwise cause the source tosupply the operating power to sensor electronics 250. In certainembodiments, this can entail harnessing sufficient power to enableprocessor 256 of sensor control device 102 to demodulate and interpret awirelessly received transition command that instructs sensor controldevice 102 to transition from a low-power mode to a higher-power mode,e.g., from an inactive mode to an activate mode. Typically, the greaterthe efficiency of the sensor control device's power management circuitry254, the lesser the number of RF communications that are required tosuccessfully transition.

The use of multiple wireless RF communications provides greater powerthan just a single RF communication of the same type, which may beinsufficient. The amount of power that is available in this RF“scavenging” process is dependent on a number of factors such as theantenna efficiency (e.g., tuning), the alignment of the RF fields(distance, position, and plane angle), and the power of the sendingcommunication circuitry (e.g., the transmitter or transceiver) withinthe reader device.

As mentioned earlier, reader device 120 can be a dedicated-use typedevice that is designed for the primary (or sole) purpose of interfacingwith sensor control device 102. Dedicated-use type reader devices 120are typically, but not always, manufactured by the same entity thatmanufactures sensor control device 102. Because the manufacturers havecontrol over the design of dedicated-use reader devices 120, they can beconfigured to transmit RF communications at a sufficiently high powerlevel that enables sensor control device 102 to transition to ahigher-power mode after receiving a minimal number of communications.

In other embodiments, however, reader devices 120 (including somededicated-use devices) have more limited capabilities and transmit atlower power levels. One example is a multi-function smartphone, wherethe function of interfacing with sensor control device 102 is anancillary one only fully implemented by those users that require it.Smartphones are designed to maximize battery life and limit theconsumption of power by the secondary circuits such as the NFCcommunication circuitry that may be used to communicate with sensorcontrol device 102. Due to size constraints, the smartphone may alsohave a smaller NFC antenna than that of a dedicated-use device. As aresult, the amount of power that can be scavenged from each RFcommunication is limited, often severely. The systems, devices, andmethods described herein, while not limited to such, are particularlysuited for smartphones and other reader devices that send RFcommunications at a relatively low power.

FIG. 15 depicts an example embodiment of sensor control device 102adapted to harness power from received NFC communications. Theembodiment here is similar to that described with respect to FIG. 2B,except that also associated with sensor electronics 250 is an internalcapacitive reservoir 255 and an external capacitive reservoir 249 forstoring the charge drawn from the received wireless communications. Thefeatures of this embodiment can also be applied to a configuration suchas that described with respect to FIG. 2C. Internal reservoir 255 can beused alone, as can external reservoir 249, or a combination of the tworeservoirs 249 and 255 can be used as shown. Capacitive reservoirs 249and 255 can include one or more capacitors electrically coupled withprocessor 256, communication circuitry 258 (adapted to send and receiveNFC communications), and power management circuitry 254. Multiplecapacitors present within reservoirs 249 and 255 can be arranged inparallel fashion to maximize the charge storage capability.

Power management circuitry 254 can perform voltage level monitoring ofpower source 260, can monitor the level of charge stored withincapacitive reservoirs 249 and 255, and can also include controlcircuitry for controlling whether power source 260 is supplying theoperating power to the remainder of sensor electronics 250. FIG. 16 is ablock diagram depicting an example embodiment of a low leakage controlcircuit 1600 that includes at least one transistor arranged to act as aswitch determining whether power source 260 is electrically connected tothe remaining electronics 250 (such that the operating power can besupplied) or electrically disconnected from the remaining electronics250 (such as when sensor control device 102 is in a low-power mode).Examples of such control circuits 1600 are described in co-pending U.S.Provisional Application No. 61/899,983, filed Nov. 5, 2013, which isincorporated by reference herein in its entirety for all purposes.

Control circuit 1600 can be responsive to a first control signal at aninput 1602 (e.g., a connection command) that causes control circuit 1600to connect power source 260 to the remaining sensor electronics 250.Control circuit 1600 can also be responsive to a second control signalat an input 1604 (e.g., a disconnection command) that causes controlcircuit 1600 to disconnect power source 260 from the remaining sensorelectronics 250. These control signals can be generated by powermanagement circuitry 254 or processor 256 using the power stored incapacitive reservoirs 249 and/or 255.

Turning now to detailed description of the RF power transfer techniques,FIG. 17AB are flow diagrams depicting an example embodiment of a method400 of supplying power to sensor control device 102 with wirelesscommunications sent by reader device 120 according to an NFC protocol.

NFC is a technique for establishing radio communication between devicesby touching them or bringing them into close proximity to each other (byway of a non-limiting example, any spaced relation up to about 1.5meters (m)). NFC devices typically send communications by generating amagnetic field with an inductive antenna at a frequency around 13.56MHz. This magnetic field induces current in a similar inductive antennain the receiving NFC device, which can then be decoded to interpret thecontents of the communication. NFC devices can be “active” or “passive”devices. Active devices typically include their own power source forgenerating voltage or current used to send NFC requests and responses.Passive devices typically do not include their own power source andrespond to a received communication by using power scavenged from thatcommunication.

The term “NFC” applies to a number of protocols (or standards) that setforth operating parameters, modulation schemes, coding, transfer speeds,frame format, and command definitions for NFC devices. The following isa non-exhaustive list of examples of these protocols, each of which(along with all of its sub-parts) is incorporated by reference herein inits entirety for all purposes: ECMA-340, ECMA-352, ISO/IEC 14443,ISO/IEC 15693, ISO/IEC 18000-3, ISO/IEC 18092, and ISO/IEC 21481.

The embodiments described herein can utilize any of the aforementionedNFC features and can utilize any NFC protocol for supplying power acrosslink 140 regardless of whether that protocol is contained in theaforementioned list or otherwise in existence at the time of thisfiling. Communication protocols other than NFC can also be used forsupplying power across link 140. For example, with supplemental powerharnessing circuitry, Wi-Fi transmissions could be used to transferpower of link 140 to sensor control device 102.

Now referring back to FIG. 17A, at 1702 a user brings reader device 120into proximity with sensor control device 102, which is in a firstlow-power mode. At 1704, the user initiates the sending of NFCcommunications from reader device 120 to sensor control device 102. Thisportion of the procedure can occur in a variety of settings. In oneexample, the user can be activating sensor control device 102 for thefirst time, before or after applying device 102 to the user's body, inwhich case sensor control device 102 may be in a power-off mode orstorage mode. The user can select an option on reader device 120 toactivate sensor control device 102 to commence that device'sinitialization for purposes of monitoring the user's analyte levels.This instruction in turn initiates the sending of the NFC communicationsfrom reader device 120.

In another example, sensor control device 102 may have already beenactivated and applied to the user's body, and has instead entered apower conservation or sleep mode that disconnects power source 260 froma portion of sensor electronics 250 not directly responsible for analytemonitoring. In such an example the user may select an option to performa scan of sensor control device 102 and retrieve the user's most currentanalyte data, which in turn initiates the sending of the NFCcommunications to “wake-up” sensor control device 102.

In FIG. 17A, the actions taken by reader device 120 are shown within box1701. The corresponding actions taken by sensor control device 102 areshown within box 1703 of FIG. 17B. In both cases, all actions can beperformed in part using the respective device's processors. At 1706 ofFIG. 17A, reader device 120 sends a supply communication according to anNFC protocol to sensor control device 102. The supply communication,which is discussed in more detail below, is selected to supply an amountof power to sensor control device 102 that is greater than the amount ofpower consumed by sensor control device 102 to interpret the supplycommunication and take the action programmed as a response to the supplycommand.

Sensor control device 102 receives the supply communication at 1730(FIG. 17B) and demodulates and reads the message contained therein at1731. At 1732, sensor control device 102 determines if the communicationcontains a transition command, which it does not at this point.Recognizing that the message contains a supply command, sensor controldevice 102 takes the appropriate action (if any) requested by the supplycommand and sends an NFC response to the command at 1733. Sensor controldevice 102 stores the excess charge (or power) from the receivedcommunication in capacitive reservoirs 249 and/or 255 at 1734. Step 1734can occur concurrently with step 1733 or later (as shown). The storageof charge in reservoirs 249 and 255 can occur only upon the receipt of avalid supply command if desired (e.g., if charge can be harnessed fromcertain random noise then that charge would not automatically be storedin reservoirs 249 and 255).

Reader device 120 receives the NFC response at 1708 (FIG. 17A) anddetermines whether it was received within a predetermined or allottedtime limit (or time window) at 1710. If the NFC response was notreceived within the predetermined time limit, then reader device 120will revert to step 1706 and send another supply command to sensorcontrol device 102. This process can repeat until a valid NFC responseis received within the predetermined time limit or until reader device120 has sent a maximum number of supply commands or otherwise reached amaximum time limit for the process.

If a valid NFC response is received within the predetermined time limit,then reader device 120 sends a transition command at 1712. Thetransition command instructs sensor control device 102 to cause powersource 260 to supply the operating power to sensor electronics 250. Thiscan entail instructing sensor control device 102 to transition from thelow-power mode to a higher power mode. The transition command can be an“activation command” that instructs sensor control device 102 toactivate and began an initialization process to ready itself for use incollecting analyte data.

Referring back to FIG. 17B, sensor control device 102 receives thecommunication containing the transition command at 1730 and demodulatesand reads it at 1731. At 1732, sensor control device 102 determines ifthe communication contains a transition command, which it does at thispoint. Recognizing that it is a transition command, sensor controldevice 102 can proceed in various manners. In the example depicted here,sensor control device 102 determines whether sufficient charge has beencollected from the one or more supply commands at 1735. Power managementcircuitry 254 can generate a flag indicating whether or not sufficientcharge has been collected and communicate it to processor 256, which cansense the flag to arrive at the determination of step 1735. Ifsufficient charge is present, then, at 1736, sensor control device 102can use that charge to cause power supply 260 to supply the operatingpower, e.g., by outputting a connection command from processor 256 tocontrol circuit 1600 that causes the connection of supply 260 to theremainder of sensor electronics 250. Sensor control device 102 can alsosend a confirmation to reader device 120 that it has successfullyexecuted the transition command. If sufficient charge is not present,then, at 1738, sensor control device 102 can send an NFC response toreader device 120 that it cannot execute the transition command.Alternatively, sensor control device 102 can take no action to conservepower.

In another example, after recognizing that a transition command has beenreceived, sensor control device 102 can forego determining whethersufficient charge is present (step 1735) and attempt to execute thecommand directly. Sensor control device 102 will either succeed or notdepending on whether sufficient charge has been collected. Sensorcontrol device 102 can then optionally perform the appropriate actiondescribed with respect to steps 1736 and 1738.

Reader device 120 monitors for receipt of confirmation that thetransition command was executed at 1714 (FIG. 17A). If a validconfirmation was received, then reader device 120 can exit the routineat 1716, having successfully supplied the requisite power to sensorcontrol device 102. If no confirmation was received, or a negativeindication was received, reader device 120 reverts to sending supplycommands at 1706 and the process can repeat as many times as permittedby the software.

As mentioned, the communication containing the supply command isselected to result in a net power gain for sensor control device 102,i.e., the power required to read and react to the communication is lessthan the power conveyed to sensor control device 102 by its receipt. Theaction that the command instructs sensor control device 102 to take maynot be a needed one at the point in time that it is sent by readerdevice 120. In other words, the command's execution may be considered tobe a negligible artifact of this power supply technique. One example ofa supply command is the inventory command set forth in ISO 15693-3,which instructs sensor control device 102 to perform the anti-collisionsequence of that protocol. In ISO 15693, each NFC request containsflags, a command code, mandatory and optional parameter fields dependingon the command, application data fields, and a cyclic redundancy check(CRC), while an NFC response contains similar fields but omits thecommand code. Sensor control device 102 can be designed to achieve netpower gains from the other commands described in ISO 15693-3, which arereiterated in Table 1 below.

TABLE 1 Command Code Type Function 01 Mandatory Inventory 02 MandatoryStay Quiet 20 Optional Read Single Block 21 Optional Write Single Block22 Optional Lock Block 23 Optional Read Multiple Blocks 24 OptionalWrite Multiple Blocks 25 Optional Select 26 Optional Reset to Ready 27Optional Write AFI 28 Optional Lock AFI 29 Optional Write DSFID  2AOptional Lock DSFID  2B Optional Get System Information  2C Optional GetMultiple Block Security Status

In the embodiment of method 1700 described with respect to FIGS. 17A-B,reader device 120 is permitted to send a large number of successivesupply commands prior to sending the transition command. It is notrequired that these supply commands be identical, as any combination ofcommands can be used, including commands that do not result in a netpower gain for sensor control device 102 (although the use of thosecommands should be minimized to obtain the maximum power supplyingeffect). In one embodiment the supply commands are a majority of thecommands that are sent. The supply commands can be sent at the outsetand followed by one or more non-supply commands, or a number ofnon-supply commands can be sent initially before the supply commands, orthe commands can be interleaved in any desired combination. Likewise,the transition command can be followed by other commands includingadditional supply commands.

Furthermore, reader device 120 need not monitor for an NFC response toeach supply command and can instead be programmed to send a specificnumber of supply commands in rapid succession. Reader device 120 canfollow with a transition command and monitor for a successful response.The sending of the supply commands in rapid succession increases thelikelihood of supplying sufficient power to sensor control device 102while minimizing the length of the process, as it is desirable to avoidsignificant delays that are perceptible to the user. In one non-limitingexample that was experimentally performed, four supply commands are sentat intervening intervals of 130 milliseconds (ms) with a transitioncommand sent every 600 ms until confirmation of success is received. Inanother non-limiting example that was also experimentally performed, tensupply commands were sent in succession followed by a transitioncommand. It was experimentally determined that ten supply commandsprovide sufficient margin to supply power across a wide range ofcommercially available smartphones under the most common conditions ofalignment and separation forming the NFC link. Other examples includethe sending of X supply commands prior to the sending of a transitioncommand, where X is 2, 3, 5, 6, 7, 8, 9, 11, 12, and so forth, whereineach cycle of sending supply commands followed by a transition commandcan be repeated X times or as many times as desired until the desiredtransition is carried out.

FIG. 18 is a conceptual diagram depicting an example situation wheremethod 1700 is implemented. Several different parameters are depictedhere in timed relationship to each other. The upper portion 1802 depictsthe activation of the RF carry power for reader device 120. The RF carrypower here is a general representation of the energy propagated byreader device 120 in the transmission of the carrier wavelengths overlink 140. In accordance with the NFC protocol, supply of the RF carrypower over link 140 can continue so long as the transmission of NFCcommands (e.g., NFC Requests) is taking place. Supply of the RF carrypower is initiated at time T₀ and ceased at time Tx. The middle portion1803 depicts the sending of the NFC communications by both reader device120 and sensor control device 102. The lower portion 1804 depicts thevoltage V_(CC) available to sensor control device 102 upon receiving andreacting to each command sent by reader device 120.

Upon initiation of the RF carry power at T₀, reader device 120 beginssending commands and V_(CC) begins to rise from a zero (or near-zero)value to a regulated maximum voltage. A communication containing supplycommand 1806-1 is received by sensor control device 102 at T₁. Sensorcontrol device 102 demodulates the communication, interprets command1806-1, and attempts to generate and send a response withinpredetermined time limit 1811-1. But as indicated by the precipitousdrop in V_(CC) that occurs after receipt of supply command 1806-1,sensor control device 102 has insufficient power to send any response,as indicated by the response failure 1807 at T_(R1).

At T₂, reader device 120 sends a second supply command 1806-2. Here,sensor control device 102 again experiences a drop in V_(CC), althoughthis drop is of less magnitude and duration because of the partialcharging of reservoirs 249 and 255, and sensor control device 102 isable to send a delayed response 1808-2 at T_(R2). Because this delayedresponse 1808-2 is not received by reader device 120 within thepredetermined time limit 1811-2, reader device 120 proceeds to sendadditional supply commands.

At T_(N), an N_(th) supply command 1806-N is received by sensor controldevice 102. The V_(CC) drop here is of even less magnitude and lessduration than the ones occurring at T₁ and T₂, and at T_(RN) sensorcontrol device 102 sends a valid response 1808-N within thepredetermined time limit 1811-N.

Upon confirming this valid response 1808-N, reader device 120 sends atransition command 1810 that is received by sensor control device 102 atT_(N+1). Sufficient charge is present to permit sensor control device102 to perform a successful mode transition and sensor control device102 sends a response 1812 with confirmation of the transition atT_(RN+1). Because of the higher power requirement to respond totransition command 1810, the V_(CC) drop is greater and longer than thatexperienced responding to the preceding supply command 1806-N.

Also provided herein are adaptive techniques that can adjust the amountof power supply to sensor control device 102 based upon one or morefailures to transition device 102 out of a low-power mode. FIG. 19 is aflow diagram depicting an example embodiment of a method 1900 ofadaptively supplying power to sensor control device 102.

At 1902, reader device 120 sends a first multitude of successive NFCcommunications containing supply commands to sensor control device 102.This first multitude of communications is selected so that it is capableof conveying a first net power to sensor control device 102. Every oneof the first multitude of communications can contain a supply command,or one of the communications, such as the last communication, cancontain a transition command. In this and any embodiment describedherein, if the sensor control device 102 can interpret and react to atransition command while maintaining a net power gain, then all supplycommands can be transition commands. At 1904, reader device 120 monitorsto determine whether a valid response was received from sensor controldevice 102 to any of the first multitude of communications, oralternatively to any transition command that was sent.

If a valid response was received to one of the supply commands, and notransition command was sent, then reader device 120 sends a transitioncommand at 1906 and determines whether a valid response was received tothe transition command at 1908. If a valid response was received thenreader device 120 can exit the software routine and optionally notifythe user that sensor control device 102 successfully transitioned to ahigher power mode (e.g., was activated) at 1910. If no valid responsewas received to one of the supply commands (see 1904) or if no validresponse was received to the transition command (see 1908), then readerdevice 120 proceeds to 1912, where another multitude of successive NFCcommunications is sent that is capable of conveying a net power that isthe same as or greater than the net power of the multitude ofcommunications that was sent immediately prior, which in this examplewas the first multitude.

The net power conveyed to sensor control device 102 can be increased ina number of ways. For example, a greater number of communications can besent over the same time period, or substantially the same time period,as was used with the preceding multitude of communications.Alternatively, the same number of communications can be sent over ashorter time period than was used with the preceding multitude ofcommunications. This approach could be used if sensor control device 102was susceptible to leakage of the received power. Also, the same numberof communications can be sent over the same time period as was used withthe first multitude, except each communication can be sent at a higherpower. In yet another example, a type of supply command can be used thatis different from the supply command in the preceding multitude aneffort to adaptively locate the type of supply command that mostefficiently transfers power to sensor control device 102. A combinationof any two or more of the aforementioned approaches can also be used.

At 1914, reader device 120 determines whether a valid response wasreceived to any of the most recently transmitted multitude ofcommunications, similar to step 1904. If so, then reader device 120proceeds to 1906 and executes it in a similar fashion to that alreadydescribed. If no valid response was received at 1914, then reader device120 proceeds to 1916 and determines if the iterative process canproceed. Factors that can be used in this assessment can include whetherreader device 120 is already sending communications at a maximumtransmit power, whether a maximum number of attempts has been reached,or whether a maximum duration of time for the entire process has beenreached. If the process can proceed then reader device 120 continues to1912 and sends yet another (in this example a third) multitude ofcommunications capable of conveying an even higher net power. If amaximum has been reached as determined at 1916, then reader device 120can exit the routine and optionally notify the user at 1918.

Reader device 120, when in the form of a smartphone, can perform themethods described herein under the control of a downloadable softwareapplication executed by applications processor 204. The smartphoneapplication can be generic to different smartphone models and canexecute an adaptive process like that of method 1900 to determine theoptimum combination of supply command timing, supply command type, ornumber of supply command communications, to supply power to eachdifferent smartphone model.

Such an adaptive process could be executed upon installation of thesoftware application, periodically in association with a scan of sensorcontrol device 102, or during a scan as part of a retry process. Ifsensor control device 102 is already activated, then reader device 120can send a notification to sensor control device 102 that it isperforming the optimization process, at which point sensor controldevice 102 can scavenge power from the subsequent supply commands andtransmit a notification back to reader device 120 as to the amount ofpower successfully scavenged. Reader device 120 can then attemptdifferent combinations of the aforementioned variables, each timereceiving an indication from sensor control device 102 as to the amountof power scavenged. The optimal combination can then be used foraccomplishing future mode transitions with that sensor control device102 or a subsequent one, and can be communicated by reader device 120back to the manufacturer for future reference, such as over an internetdata connection.

Although many of the embodiments described herein are done so in thecontext of transitioning from a lower power mode to a higher power modewith the aid of a transition command, the power scavenging technique canbe used in other contexts as well. For example, these embodiments can beused to prolong the battery life by sending supply commands even aftersensor control device 102 has transitioned to the higher power mode(activated). Supply commands can be sent automatically during everycommunication session between reader device 120 and sensor controldevice 102, or whenever reader device 120 sends a command known torequire greater power consumption than usual. Reader device 120 may beprogrammed to send supply commands whenever a predetermined subset ofNFC commands are transmitted (e.g., an NFC command to perform a scan ofthe user's analyte level, process the results, and transmit back toreader device 120 is one such command that consumes a large amount ofpower). Reader device 120 can also send supply commands whenever theyare requested by sensor control device 102 during a communicationsession.

Unless otherwise noted herein, each of the methods steps described inthe aforementioned embodiments can be performed by processor 256 orcommunication circuitry 258 (e.g., a transceiver, or a separate receiveror transmitter). Steps performed by these components can be done at thedirection of software programming executed by processor 256.

While many of the embodiments described herein relate to activation of adevice, these embodiments are not mutually exclusive. Stateddifferently, a subject device can include any combination of one or moreof the embodiments described herein, including multiple differentmechanisms for activating that device.

Generally, embodiments of the present disclosure are used with in vivosystems, devices, and methods for detecting at least one analyte, suchas glucose, in body fluid (e.g., transcutaneously, subcutaneously withinthe ISF or blood, or within the dermal fluid of the dermal layer). Invivo analyte monitoring systems can be differentiated from “in vitro”systems that contact a biological sample outside of the body (or rather“ex vivo”) and that typically include a meter device that has a port forreceiving an analyte test strip carrying the biological sample of theuser, which can be analyzed to determine the user's blood sugar level.Many in vitro systems require a “finger stick” to obtain the biologicalsample. In vivo analyte monitoring systems, however, can operate withoutthe need for finger stick calibration.

Many embodiments include in vivo analyte sensors arranged so that atleast a portion of the sensor is positioned in the body of a user toobtain information about at least one analyte of the body. However, theembodiments described herein can be used with in vivo analyte monitoringsystems that incorporate in vitro capability, as well has purely invitro or ex vivo analyte monitoring systems. Furthermore, theembodiments described herein can be used in systems, devices, andmethods outside of the analyte monitoring field, either in other medicaldevice fields, or any other field that requires the supply of power toone device from another.

Sensor Configurations

Analytes that may be monitored with system 100 include, but are notlimited to, acetyl choline, amylase, bilirubin, cholesterol, chorionicgonadotropin, glycosylated hemoglobin (HbAlc), creatine kinase (e.g.,CK-MB), creatine, creatinine, DNA, fructosamine, glucose, glucosederivatives, glutamine, growth hormones, hormones, ketones, ketonebodies, lactate, oxygen, peroxide, prostate-specific antigen,prothrombin, RNA, thyroid stimulating hormone, and troponin. Theconcentration of drugs, such as, for example, antibiotics (e.g.,gentamicin, vancomycin, and the like), digitoxin, digoxin, drugs ofabuse, theophylline, and warfarin, may also be monitored. In embodimentsthat monitor more than one analyte, the analytes may be monitored at thesame or different times with a single sensor or with a plurality ofsensors which may use the same electronics (e.g., simultaneously) orwith different electronics of sensor control device 102.

Analyte sensor 104 may include an analyte-responsive enzyme to provide asensing element. Some analytes, such as oxygen, can be directlyelectrooxidized or electroreduced on sensor 104, and more specificallyat least on a working electrode (not shown) of a sensor 104. Otheranalytes, such as glucose and lactate, require the presence of at leastone electron transfer agent and/or at least one catalyst to facilitatethe electrooxidation or electroreduction of the analyte. Catalysts mayalso be used for those analytes, such as oxygen, that can be directlyelectrooxidized or electroreduced on the working electrode. For theseanalytes, each working electrode includes a sensing element proximate toor on a surface of a working electrode. In many embodiments, a sensingelement is formed near or on only a small portion of at least a workingelectrode.

Each sensing element includes one or more components constructed tofacilitate the electrochemical oxidation or reduction of the analyte.The sensing element may include, for example, a catalyst to catalyze areaction of the analyte and produce a response at the working electrode,an electron transfer agent to transfer electrons between the analyte andthe working electrode (or other component), or both.

Electron transfer agents that may be employed are electroreducible andelectrooxidizable ions or molecules having redox potentials that are afew hundred millivolts above or below the redox potential of thestandard calomel electrode (SCE). The electron transfer agent may beorganic, organometallic, or inorganic. Examples of organic redox speciesare quinones and species that in their oxidized state have quinoidstructures, such as Nile blue and indophenol. Examples of organometallicredox species are metallocenes including ferrocene. Examples ofinorganic redox species are hexacyanoferrate (III), ruthenium hexamine,etc. Additional examples include those described in U.S. Pat. Nos.6,736,957, 7,501,053 and 7,754,093, the disclosures of each of which areincorporated herein by reference in their entirety.

In certain embodiments, electron transfer agents have structures orcharges which prevent or substantially reduce the diffusional loss ofthe electron transfer agent during the period of time that the sample isbeing analyzed. For example, electron transfer agents include but arenot limited to a redox species, e.g., bound to a polymer which can inturn be disposed on or near the working electrode. The bond between theredox species and the polymer may be covalent, coordinative, or ionic.Although any organic, organometallic or inorganic redox species may bebound to a polymer and used as an electron transfer agent, in certainembodiments the redox species is a transition metal compound or complex,e.g., osmium, ruthenium, iron, and cobalt compounds or complexes. Itwill be recognized that many redox species described for use with apolymeric component may also be used, without a polymeric component.

Embodiments of polymeric electron transfer agents may contain a redoxspecies covalently bound in a polymeric composition. An example of thistype of mediator is poly(vinylferrocene). Another type of electrontransfer agent contains an ionically-bound redox species. This type ofmediator may include a charged polymer coupled to an oppositely chargedredox species. Examples of this type of mediator include a negativelycharged polymer coupled to a positively charged redox species such as anosmium or ruthenium polypyridyl cation.

Another example of an ionically-bound mediator is a positively chargedpolymer including quaternized poly (4-vinyl pyridine) or poly(1-vinylimidazole) coupled to a negatively charged redox species such asferricyanide or ferrocyanide. In other embodiments, electron transferagents include a redox species coordinatively bound to a polymer. Forexample, the mediator may be formed by coordination of an osmium orcobalt 2,2′-bipyridyl complex to poly(1-vinyl imidazole) or poly(4-vinylpyridine).

Suitable electron transfer agents are osmium transition metal complexeswith one or more ligands, each ligand having a nitrogen-containingheterocycle such as 2,2′-bipyridine, 1,10-phenanthroline, 1-methyl,2-pyridyl biimidazole, or derivatives thereof. The electron transferagents may also have one or more ligands covalently bound in a polymer,each ligand having at least one nitrogen-containing heterocycle, such aspyridine, imidazole, or derivatives thereof. One example of an electrontransfer agent includes (a) a polymer or copolymer having pyridine orimidazole functional groups and (b) osmium cations complexed with twoligands, each ligand containing 2,2′-bipyridine, 1,10-phenanthroline, orderivatives thereof, the two ligands not necessarily being the same.Some derivatives of 2,2′-bipyridine for complexation with the osmiumcation include but are not limited to 4,4′-dimethyl-2,2′-bipyridine andmono-, di-, and polyalkoxy-2,2′-bipyridines, including4,4′-dimethoxy-2,2′-bipyridine. Derivatives of 1,10-phenanthroline forcomplexation with the osmium cation include but are not limited to4,7-dimethyl-1,10-phenanthroline and mono, di-, andpolyalkoxy-1,10-phenanthrolines, such as4,7-dimethoxy-1,10-phenanthroline. Polymers for complexation with theosmium cation include but are not limited to polymers and copolymers ofpoly(1-vinyl imidazole) (referred to as “PVI”) and poly(4-vinylpyridine) (referred to as “PVP”). Suitable copolymer substituents ofpoly(1-vinyl imidazole) include acrylonitrile, acrylamide, andsubstituted or quaternized N-vinyl imidazole, e.g., electron transferagents with osmium complexed to a polymer or copolymer of poly(1-vinylimidazole).

Embodiments may employ electron transfer agents having a redox potentialranging from about −200 mV to about +200 mV versus the standard calomelelectrode (SCE). The sensing elements may also include a catalyst whichis capable of catalyzing a reaction of the analyte. The catalyst mayalso, in some embodiments, act as an electron transfer agent. Oneexample of a suitable catalyst is an enzyme which catalyzes a reactionof the analyte. For example, a catalyst, including a glucose oxidase,glucose dehydrogenase (e.g., pyrroloquinoline quinone (PQQ), dependentglucose dehydrogenase, flavine adenine dinucleotide (FAD) dependentglucose dehydrogenase, or nicotinamide adenine dinucleotide (NAD)dependent glucose dehydrogenase), may be used when the analyte ofinterest is glucose. A lactate oxidase or lactate dehydrogenase may beused when the analyte of interest is lactate. Laccase may be used whenthe analyte of interest is oxygen or when oxygen is generated orconsumed in response to a reaction of the analyte.

In certain embodiments, a catalyst may be attached to a polymer, crosslinking the catalyst with another electron transfer agent, which, asdescribed above, may be polymeric. A second catalyst may also be used incertain embodiments. This second catalyst may be used to catalyze areaction of a product compound resulting from the catalyzed reaction ofthe analyte. The second catalyst may operate with an electron transferagent to electrolyze the product compound to generate a signal at theworking electrode. Alternatively, a second catalyst may be provided inan interferent-eliminating layer to catalyze reactions that removeinterferents.

In certain embodiments, the sensor works at a low oxidizing potential,e.g., a potential of about +40 mV vs. Ag/AgCl. These sensing elementsuse, for example, an osmium (Os)-based mediator constructed for lowpotential operation. Accordingly, in certain embodiments the sensingelements are redox active components that include: (1) osmium-basedmediator molecules that include (bidente) ligands, and (2) glucoseoxidase enzyme molecules. These two constituents are combined togetherin the sensing elements of the sensor.

A number of embodiments of sensor configurations that may be used insystem 100 are described in Int'l Publication No. WO 2012/174538, titled“Connectors for Making Connections between Analyte Sensors and OtherDevices,” and also in U.S. Pat. No. 8,435,682, titled “Biological FuelCell and Methods,” both of which are incorporated by reference herein intheir entirety for all purposes. Particular attention is drawn toparagraphs 121-145 of the '528 Publication, several of which arereproduced herein.

All features, elements, components, functions, and steps described withrespect to any embodiment provided herein are intended to be freelycombinable and substitutable with those from any other embodiment. If acertain feature, element, component, function, or step is described withrespect to only one embodiment, then it should be understood that thatfeature, element, component, function, or step can be used with everyother embodiment described herein unless explicitly stated otherwise.This paragraph therefore serves as antecedent basis and written supportfor the introduction of claims, at any time, that combine features,elements, components, functions, and steps from different embodiments,or that substitute features, elements, components, functions, and stepsfrom one embodiment with those of another, even if the followingdescription does not explicitly state, in a particular instance, thatsuch combinations or substitutions are possible. Express recitation ofevery possible combination and substitution is overly burdensome,especially given that the permissibility of each and every suchcombination and substitution will be readily recognized by those ofordinary skill in the art upon reading this description.

In many instances, entities are described herein as being coupled toother entities. It should be understood that the terms “coupled” and“connected” (or any of their forms) are used interchangeably herein and,in both cases, are generic to the direct coupling of two entities(without any non-negligible (e.g., parasitic) intervening entities) andthe indirect coupling of two entities (with one or more non-negligibleintervening entities). Where entities are shown as being directlycoupled together, or described as coupled together without descriptionof any intervening entity, it should be understood that those entitiescan be indirectly coupled together as well unless the context clearlydictates otherwise.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise.

While the embodiments are susceptible to various modifications andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that these embodiments are not to be limited to the particularform disclosed, but to the contrary, these embodiments are to cover allmodifications, equivalents, and alternatives falling within the spiritof the disclosure. Furthermore, any features, functions, steps, orelements of the embodiments may be recited in or added to the claims, aswell as negative limitations that define the inventive scope of theclaims by features, functions, steps, or elements that are not withinthat scope.

1-20. (canceled)
 21. An apparatus for in vivo glucose monitoring of auser with an in vivo glucose sensor, the apparatus comprising: (1) asensor control device configured to be worn on the user's skin, thesensor control device comprising: a sensor control device housingdefining an enclosure; and sensor electronics disposed in the enclosure,the sensor electronics comprising in vivo glucose monitoring circuitry,a power source, and a magnetic activation sensor; wherein the in vivoglucose monitoring circuitry is configured to electrically couple withan in vivo glucose sensor having a distal end comprising aglucose-responsive enzyme, and wherein the magnetic activation sensor isconfigured to transition the sensor control device from a first powerstate to a second power state upon removal of a magnetic field; (2) anapplicator, comprising: an applicator housing; a removable end capconfigured to couple with the applicator housing by a plurality ofcomplimentary threads, wherein the applicator housing and the removableend cap define an interior of the applicator; a sharp; and a magnetconfigured to generate the magnetic field, wherein the sensor controldevice is disposed in the interior of the applicator prior toapplication on the user's skin, wherein the applicator is configured tocause the sharp to insert the distal end of the in vivo glucose sensorunder the user's skin and apply the sensor control device on the user'sskin; wherein the sharp is configured to automatically retract after thedistal end of the in vivo glucose sensor is inserted under the user'sskin, and wherein the removal of the magnetic field and the transitionof the sensor control device from the first power state to the secondpower state occur after the automatic retraction of the sharp and theapplication of the sensor control device on the user's skin.
 22. Theapparatus of claim 21, wherein the sensor control device furthercomprises a first wireless communication circuitry disposed in theenclosure and configured to transmit glucose data to a reader device viaa Bluetooth communication protocol.
 23. The apparatus of claim 22,wherein the reader device is a smart phone.
 24. The apparatus of claim23, wherein the sensor control device further comprises non-transitorymemory and one or more processors disposed in the enclosure, the one ormore processors including an application specific integrated circuit(ASIC).
 25. The apparatus of claim 22, wherein the sensor control devicefurther comprises a second wireless communication circuitry disposed inthe enclosure and configured to communicate data according to a nearfield communication (NFC) protocol.
 26. The apparatus of claim 25,wherein the second power state is a normal operation mode.
 27. Theapparatus of claim 25, wherein the power supply is configured to supplypower to the in vivo glucose monitoring circuitry when the sensorcontrol device is in the second power state.
 28. The apparatus of claim25, wherein the power supply is configured to not supply power to the invivo glucose monitoring circuitry when the sensor control device is inthe first power state.
 29. The apparatus of claim 28, wherein the firstpower state is a powered-off state.
 30. The apparatus of claim 28,wherein the first power state is a low-power state.
 31. The apparatus ofclaim 28, wherein the first power state is a sleep state.
 32. Theapparatus of claim 28, wherein the first power state is a storage mode.33. The apparatus of claim 25, wherein the sensor control device furthercomprises an adhesive patch configured to attach the sensor controldevice to the user's skin.
 34. The apparatus of claim 33, wherein the invivo glucose sensor is configured to extend through the adhesive patchand project away from the sensor control device housing, and wherein theadhesive patch is configured to contact the user's skin when the sharpinserts the distal end of the in vivo glucose sensor under the user'sskin.
 35. The apparatus of claim 34, wherein the applicator furthercomprises integrally formed grip features and a translating sheath. 36.The apparatus of claim 34, wherein the removable end cap includes one ormore openings configured to allow for the passage of ethylene oxide forsterilizing the interior of the applicator.
 37. The apparatus of claim36, wherein the removable end cap further includes a gas-permeable sealdisposed over the one or more openings.
 38. The apparatus of claim 21,wherein the magnetic activation sensor is a Reed switch.
 39. Theapparatus of claim 21, wherein the magnetic activation sensor is a Halleffect sensor.
 40. The apparatus of claim 21, wherein the distal end ofthe in vivo glucose sensor comprises a working electrode.
 41. Theapparatus of claim 40, wherein the glucose-responsive enzyme is disposedon the surface of the working electrode.
 42. The apparatus of claim 41,wherein glucose-responsive enzyme is glucose oxidase.
 43. The apparatusof claim 21, wherein the sensor control device housing comprises a topshell and a base portion.
 44. The apparatus of claim 43, wherein the topshell and the base portion are welded together such that the sensorelectronics are sealed within the enclosure of the sensor controldevice.
 45. The apparatus of claim 43, wherein the top shell and thebase portion are coupled via a snap-fit interface such that the sensorelectronics are sealed within the enclosure of the sensor controldevice.
 46. The apparatus of claim 43, wherein the top shell and thebase portion form a single over-molded unit comprising a thermoplasticmaterial, and wherein the single over-molded unit seals the sensorelectronics within the enclosure of the sensor control device.